Development of a Small Diameter Shock Tu

In this study, we developed a diaphragmless driver section with two pistons to generate the shock wave in small diameter tubes. An optical system using a He-Ne laser was constructed to define the main piston opening time. We measured the trajectories of the main piston under various initial driver pressures and derived the motion equation for the main piston based on a simple motion model. To achieve contactless measurement of shock waves, a laser differential interferometer was constructed. The shock waves generated by our diaphragmless driver section in 2 mm and 3 mm inner diameter tubes were measured using the laser differential interferometer. The Mach number of the shock wave and the density ratio across the shock wave were calculated from the interference signals obtained from the measurements. Additionally, we obtained Mach number distributions along the axial direction of the tubes and established the relationship between shock wave location and time through the shock wave diagram. The results indicate that the friction effect between the test gas and the inner wall of the tubes increases as the inner diameter decreases.